Fewer than one in five broadband firms are warning consumers that actual
speeds may be slower than estimates, Ofcom has found.

The communications regulator said that although most consumers are now given estimates of the broadband speeds they should receive when signing up for a new internet package, just 17 per cent were warned that additional, domestic factors could make the speed they receive substantially lower.

An Ofcom spokesman said the figure, down from 19 per cent last year, was a cause of realconcern. “Where we’ve seen improvement in other areas, these certain areas need to be a core focus,” said the spokesman. “It is in the internet service providers’ interest to make this voluntary code work.”

Broadband providers now offer consumers estimates of the speed they will receive when they sign up for a package, which typically claims it will offer speeds "up to" a headline figure. The firms, including BT and TalkTalk, are however supposed to warn that estimates are not always accurate and could be affected by a customer's house's wiring or interference from other appliances.

The survey, produced as the result of a mystery shopping exercise by the regulator, found that Ofcom’s Voluntary Code of Practice on Broadband Speeds meant that 96 per cent of all users signing up for a new broadband package were provided with a speed estimate, up from 93 per cent last year.

The research reveals that ISPs provided speed estimates without prompting in 68 per cent of calls.

Two in five mystery shoppers were given information about factors that can affect their broadband speed, up from from 34 per cent in 2012.

Of the provders surveyed, EE, Plusnet and Karoo all provided speeds information in 100 per cent of mystery shopping calls.

O2 was least likely to provide a speed range, supplying this in 58 per cent of calls. Talk Talk (47 per cent of calls) and O2 (55 per cent) were the least likely to provide an unprompted speed estimate.

Ofcom said it would take action to improve compliance with the voluntary code, introduced in 2010, and perform further mystery shopping exercises. It added that it will also be undertaking a full review of the Code to ensure that it best serves consumers’ needs, taking particular account of increased take-up of superfast broadband packages.

Claudio Pollack, Ofcom’s Consumer Group Director, said: “The results of our mystery shopping are encouraging, with the quality of information being provided to consumers at the point of sale improving overall.

“However, the research has identified areas where providers need to do more to improve, particularly in terms of providing speeds information spontaneously and early in the sales process. We’re already working with providers to ensure they tighten up their sales processes where we’ve identified concerns.”